I have a Linksys WRT54G wireless router, hardware version 1.1, used daily since early 2004. I recently upgraded from firmware 4.20.7 to firmware 4.21.1. When I use the Access Restrictions tab to enable/ disable one of the PCs in my home, an operation done successfully for many months, and then Save Settings, I see "The values you entered are invalid. Please try again." There is no further explanation of what the problem is, and I know the settings I am trying to save worked before. I went back to firmware 4.20.7 and the exact same settings are accepted with no problem. I plan to stay away from version
4.21.1. A web search shows other users unhappy with this firmware also, such as the following currently-unanswered post on the Linksys website:
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